Throttle jammed full on at xxxmph
Discussion
Came across one of these on the motorway last night:
[pic]http://www.lexus.com/assets/models/performance/photo/sc_perf_img.jpg[/pic]
It came up behind me pretty swiftly, and took off like a scalded cat after I moved over. Curiousity got the better of me as I had no idea what it was, and it passed so quickly I didn't make out a badge.
When it was baulked by traffic again I swung out behind. Again he was off once the gates were opened, and I floored the Chim to see just how fast that thing was. Impressive, but not quite as fast as the Chim, as I was slowly gaining ground. Ease off.
AAAARRRRRGGGHHH! Still gaining ground, pedal is slack and on the floor, pulling it up with my foot hooked under has no effect! Yep, I can see its a Lexus now alright. :eek: I cut the ignition and coasted in to the hard shoulder.
The throttle linkage was solidly jammed full open, and took a few flicks to free up. Liberal sprays with WD40 later I was on my way again.
Truly scary moment, and if the driver of the Lexus is reading, sorry mate I wasn't being a smart arse driving up your chuffer like that!
Incidentally, it takes a very long time to coast to a hold from high speed!
[pic]http://www.lexus.com/assets/models/performance/photo/sc_perf_img.jpg[/pic]
It came up behind me pretty swiftly, and took off like a scalded cat after I moved over. Curiousity got the better of me as I had no idea what it was, and it passed so quickly I didn't make out a badge.
When it was baulked by traffic again I swung out behind. Again he was off once the gates were opened, and I floored the Chim to see just how fast that thing was. Impressive, but not quite as fast as the Chim, as I was slowly gaining ground. Ease off.
AAAARRRRRGGGHHH! Still gaining ground, pedal is slack and on the floor, pulling it up with my foot hooked under has no effect! Yep, I can see its a Lexus now alright. :eek: I cut the ignition and coasted in to the hard shoulder.
The throttle linkage was solidly jammed full open, and took a few flicks to free up. Liberal sprays with WD40 later I was on my way again.
Truly scary moment, and if the driver of the Lexus is reading, sorry mate I wasn't being a smart arse driving up your chuffer like that!
Incidentally, it takes a very long time to coast to a hold from high speed!
Sorry to hear that mate. Had it happen once in mine, cleaned up the linkages and never happened since. Best thing to do is just knock it out of gear, at least then you still retain power steering and servo assistance on the brakes.
I've also come up against one of those Lexus 430 things. Was truly surprised how quick they were, but then again its got a modern 4.3l V6 (I think) lump in it. They don't go round corners though and also look damned ugly. At least we know which driver has the most smiles per mile in their car, rather than a quick but extremely bland cabriolet.
I've also come up against one of those Lexus 430 things. Was truly surprised how quick they were, but then again its got a modern 4.3l V6 (I think) lump in it. They don't go round corners though and also look damned ugly. At least we know which driver has the most smiles per mile in their car, rather than a quick but extremely bland cabriolet.
- Could I suggest that you inspect the whole of your throttle linkage and assembly VERY carefully. I had this happen , but fortunatley when I was staionary and just holding the revs at 3000 checking the oil pressure, only to find that nothing happened when I took my foot off the pedal. In my case one of the nuts (of the pair of nuts and bolts that secure the throttle spindle bearing to the arm which carries the engine end of the cable), had come off and the bolt had slipped backwards and jammed under the crank arm (to which the cable is connected). It is such a silly little fault yet it could have had alarming consequences on the road. I now regularly check the security of these and the rest of the linkage.
Sounds scary!
I had a similar problem last week. In my case one of the intake pipes fell off, which on a MAP-based system is equivalent to full throttle. So rather than the throttle sticking open, it actually went full throttle on its own.
As an aside, if the throttle is wide open then you have no brake servo, regardless of whether the engine is switched on and/or in gear. But by keeping it in gear (switched off) at least you get the benefit of some engine braking in addition to the foot brake.
I had a similar problem last week. In my case one of the intake pipes fell off, which on a MAP-based system is equivalent to full throttle. So rather than the throttle sticking open, it actually went full throttle on its own.
As an aside, if the throttle is wide open then you have no brake servo, regardless of whether the engine is switched on and/or in gear. But by keeping it in gear (switched off) at least you get the benefit of some engine braking in addition to the foot brake.
I guess if the ECU was smart enough it could work out that full load on the MAP sensor with the TPS showing throttle closed isn't right, but the OMEX ECU I'm using doesn't seem to be smart enough. I'll have to re-read the manual for the anti-lag system and see if I can use that to introduce a secondary rev limit triggered off the throttle pot, but I've got more important things to concentrate at the moment ...
Tahiti - I will be stripping and cleaning the whole assembly just to make sure, and possibly fitting a new cable to be on the safe side. This is one experience I don't want to repeat.
The throttle were fully open, so just knocking into neutral wasn't an option. I dippped the clutch immediately, and it was bouncing off the limiter instantly. The clutch went in for life preservation, the ignition went off for wallet preservation!
I'll know when I strip and clean the mechanism; it was difficult to see in the dark on the hard shoulder, but it seemed it has gone "over cam" and stuck, if that makes sense.
Pete - never thought about the full throttle/no vacuum/no servo before - its not like you ever try braking while your right foot is hard to the floor! Seems to make sense though. I certainly had no servo assist at all, which I was a little surprised at as you normally get some assist from residual vacuum after you switch off. I guess I was luckier than I thought; if the Lexus had hit the brakes just as my throttles jammed I'd have been toast.
Incidentally, the Lexus was a metallic bronze, and it looked rather nice I thought. Big, and sort of chiselled looking. Not a girls cabrio. Unless I'm discovering my feminine side!
The throttle were fully open, so just knocking into neutral wasn't an option. I dippped the clutch immediately, and it was bouncing off the limiter instantly. The clutch went in for life preservation, the ignition went off for wallet preservation!
I'll know when I strip and clean the mechanism; it was difficult to see in the dark on the hard shoulder, but it seemed it has gone "over cam" and stuck, if that makes sense.
Pete - never thought about the full throttle/no vacuum/no servo before - its not like you ever try braking while your right foot is hard to the floor! Seems to make sense though. I certainly had no servo assist at all, which I was a little surprised at as you normally get some assist from residual vacuum after you switch off. I guess I was luckier than I thought; if the Lexus had hit the brakes just as my throttles jammed I'd have been toast.
Incidentally, the Lexus was a metallic bronze, and it looked rather nice I thought. Big, and sort of chiselled looking. Not a girls cabrio. Unless I'm discovering my feminine side!
Peter,
Fair enough. Just an aside, on the MS system there seems to be an option for a crude traction control, where by if engine rev's increase by the eqiuvalent of xxxx rpm per second it cuts fuel or spark or both.
Alternatively could you not have an extra position on the fuel/spark map where full load MAP and 0% throttle = no fuel? Just throwing ideas about.
Glad everyone is ok though!
Regards
Iain
Fair enough. Just an aside, on the MS system there seems to be an option for a crude traction control, where by if engine rev's increase by the eqiuvalent of xxxx rpm per second it cuts fuel or spark or both.
Alternatively could you not have an extra position on the fuel/spark map where full load MAP and 0% throttle = no fuel? Just throwing ideas about.
Glad everyone is ok though!
Regards
Iain
Hughesie2 said:
4.3l V6 (I think) lump in it.
V8 i think, Whitey had one as a hire car for a while...
4.3l V8. Slushbox only though and no torque so I'm surprised you thought it was fast.
I had one as a hire car for 2 weeks and my Griff would have passed it as if the Lexus was in reverse. And don't talk to it about corners and the traction control is shite and the seat belts rattle with the roof down and the gearbox is awful and the switch controls are out of a 1980s Toyota Starlet and someone called me a w*nker while I was driving it ...
Horrible things.
Ian A.
GreenV8S said:
I guess if the ECU was smart enough it could work out that full load on the MAP sensor with the TPS showing throttle closed isn't right, but the OMEX ECU I'm using doesn't seem to be smart enough. I'll have to re-read the manual for the anti-lag system and see if I can use that to introduce a secondary rev limit triggered off the throttle pot, but I've got more important things to concentrate at the moment ...
Hi Peter, this is related as my throttle stuck open in 2nd, but iam interested in you thoughts on the Omex. I was considering it, having just spent £7.5k apparantly its "the icing on the cake". If you think this will be boring and off topic, maybe you could email me.
IPAddis said:It was no slouch, quick enough for me to think "what the hell was that" when it went past - and that was accelerating past me from the same steady speed. It certainly gathered up its skirts.
4.3l V8. Slushbox only though and no torque so I'm surprised you thought it was fast.
david beer said:
Hi Peter, this is related as my throttle stuck open in 2nd, but iam interested in you thoughts on the Omex. I was considering it, having just spent £7.5k apparantly its "the icing on the cake". If you think this will be boring and off topic, maybe you could email me.
It looks like a reasonable enough system, there are some things about that seem rather strange but no doubt there is some good reason for them. The user interface is pretty unfriendly but it is adequate. If you're considering doing the installation yourself you might be a bit bothered to know that there is no online documentation, the paper documentation is woefully inadequate (all the interesting bits just say 'call Omex'), there is no Omex user group or support forum, the support consists of two guys who seems to really know their stuff but appear to be very overworked, rarely respond to emails and are tricky to contact by phone. If you're planning to pay somebody else to install it and set it up for you this is unlikely to be a problem though. The system does come recommended by people who know their ECUs though, so presumably once set up they can be made to work well. (I wouldn't know, I'm still trying to work out wtf it thinks it's doing with my ignition timing ...)
victormeldrew said:
Incidentally, it takes a very long time to coast to a hold from high speed!
Matter of interest, not being blessed with a TVR, why does it take a long time to stop when your coasting, is the breaking affeced by the engine not running, not being smart, just curious?
GreenV8S said:
Matter of interest, not being blessed with a TVR, why does it take a long time to stop when your coasting, is the breaking affeced by the engine not running, not being smart, just curious?
The brake servo doesn't work when the throttle is wide open.
Thanks for info, have a nice day.
jonathant said:Yes, I was careful not to turn it all the way back. Having the steering lock on as well would have really made my day.
My 99 Chim does, but only when you pull out the key (like most cars).
It would have been like my experience a few days previous in the Audi (80mph M1 outside lane with dead engine and no PAS) except, er, a bit faster.
I'm not having much luck with cars at the moment!
victormeldrew said:
My 99 Chim does, but only when you pull out the key (like most cars).
Yes, I was careful not to turn it all the way back. Having the steering lock on as well would have really made my day.
It would have been like my experience a few days previous in the Audi (80mph M1 outside lane with dead engine and no PAS) except, er, a bit faster.
I'm not having much luck with cars at the moment!
When you have a dead engine and hense no PAS is it just like an ordinary car without PAS?, if so apart from the fact its harder to turn the wheels when your slow or stationary, wouldnt make much differnce just rolling along the motorway coming to a standstill on the hard shoulder, would it?
Or do some cars really suffer with PAS loss, but from a safety standpoint, I would guess they would not.
Although at slower speeds you would of course notice it.
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